Method of making footwear having a polyurethane sole

ABSTRACT

METHOD FOR PRODUCING FOOTWEAR HAVING A POLYURTHANE SOLE OF DESIRED SPECIFIC GRAVITY WHICH COMPRISES CASTING A LIQUID,POLYURTHANE-FORMING MATERIAL INTO A SHOE SOLE MOULD MAINTAINED AT A DEFINATE INITIAL TEMPERATURE,MOUNTING A LAST WHICH BEARS A SHOE UPPER ON THE SHOE SOLE MOULD, ALLOWING THE POLYURTHANE-FORMING MATERIAL TO FOAM AND ADHERE TO THE BOTTOM OF THE UPPER, AND THEN REMOVING THE MOLD AND LAST FROM THE PRODUCT AND CURING THE FOAMED SHOE SOLE.

June 4, 1974 sHQJl OLA ETAL 3,814,781

METHOD OF MAKING FOOTWEAR HAVING A POLYURETHANE SOLE Original FiledSept. 16, 1968 5 Sheets-Sheet l FIGI r, ATTORNEYS June 4, 1974AsI-IOJTOLA ETAT. 3,814,781 I METHOD OF MAKING FOOTWEAR HAVING APOLYURETHANE SOLE I.

original Filed sept. 1 6, 1968 J- 3 sheets-Sheet 2 sHOE UPPER LAsT MOULDMAINTAINED AT A sEwING GOOLING OR HEATING DEE'NED TEMPERATURE CASTING YMOUNTING E FITTING OE THE LAST GURING CLEANING AND REMOVAL OE THE MOULDREAGGEMDLY I OF THE MOULD POGT-GURING REMOVAL OE THE LAST PACKINGTNVENTORS SHOJI OKA TAKAGHI WAKADAYASHI /gffwel/{WCZZ ATTORNEYS June 4,1974 sHOJrOLA ETAL 3,814,781

METHOD OF MAKING FOOTWEAR HAVING A POLYURETHANE SOLE 3 Sheets-Sheet 5Original Filed Sept. 16, 1968 HOO y mvENToRs sHoJl oKA TAKASHIwAKABAYAsHl www United States Patent.

, 3,814,781 METHOD OF MAKING FOOTWEAR HAVING A POLYURETHANE SOLE ShojiOka and Takashi Wakabayashi, Osaka, Japan, as-

signors to The Toyo Rubber Industry Co., Ltd., Osaka, Ja an Continuationof application Ser. No. 767,899, Sept. 16, 1968, which is acontinuation-impart of application Ser. No. 594,581, Nov. 15, 1966, bothnow abandoned. This application Apr. 19, 1972, Ser. No. 245,620

Int. Cl. B29h 7/ 08 U.S. Cl. 264-54 9 Claims ABSTRACT OF THE DISCLOSUREMethod for producing footwear having a polyurethane sole of desiredspeciiic gravity which comprises casting a liquid, polyurethane-formingmaterial into a shoe sole mould maintained at a delinite initialtemperature, mounting a last which bears a shoe upper on the shoe solemould, allowing the polyurethane-forming material to foam and adhere tothe bottom of the upper, and then removing the mould and last from theproduct and curing the foamed shoe sole.

This is a continuation, of application Ser. No. 767,899, filed Sept. 16,1968, now abandoned, which in turn is a continuation-in-part f Ser. No.594,581, Nov. 15, 1966, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to a method of making footwear having a polyurethane foam sole.

Description of the prior art In prior methods of making shoes, a shoeupper, formed by cementing or sewing together several parts or elementstogether with a cemented inner sole member, is mounted on a last. Cementis then applied to the bottom of the shoe upper and dried. A rubber tapeis wound on and rolled to the bottom of the shoe upper. Then a solemember cemented to the shoe upper and the assembly thus built up, ifdesired, after treatment with a milled roller, is hung on a carrier andvulcanized in a vulcanizing pan using steam or hot air. Thus, the priormethods consist of many stages and need a number of workers to completethe operation. It has been proposed to make shoes with a syntheticresinous sole by injecting under high pressure a hot melt of athermoplastic resin such as, eg., vinyl, polyamide or polyester resins,into a shoe soleforming mould to form a synthetic resinous shoe soleadherent or firmly bonded to a shoe upper, and taking out the finishedshoe from the mould after cooling and solidilcation of the resin. Thismethod, however, has shortcomings in that (l) there is need, in carryingout this method, for employing a high-priced injection machine and aprecisely fabricated metal mould, (2) the shoe upper member is apt to bebroken up since it is strained by being forcibly pressed against themould, (3) it is very ditlicult to prevent leakage of resin because ofthe high pressure imposed on the resin, (4) the method itself isinefficient due to the necessity of heating the mould to a hightemperature and cooling it for ease of withdrawal of the finishedproduct therefrom, (5) it is diflicult to obtain uniform adhesionbetween the resinous sole and shoe upper, and (6) the upper member mustbe made out of a thermally resistant and tenacious material.

In contrast, since the material to be employed in the method of thisinvention is a liquid of a low viscosity it can be poured or introducedinto the mould by means of,

' egg., a Vgear pump or plunger pump without any diliiculty.

In addition, in the method of this invention, it isv unnecessary for themould to be formed of a material of'hig'h strength and to be soprecisely fabricated, since in the moulding process the mould faces anelastomeric material under the mere expanding pressure of the foam.Furthermore, by the choiceof the initial mould temperature, the shoesole to be formed can be varied from a soft sponge-like one to a rigidsolid-like one.

SUMMARY OF THE INVENTION It has been found that footwear having apolyurethane sole with controllable density may be formed by a simpleprocess which comprises introducing a liquid, polyurethane foam-formingmaterial into a shoe sole-forming mould having a recess in'the form of ashoe sole, the shoe sole mould being maintained at a definitetemperature to control the density of the inal foamed sole. A last,which carries ashoe upper is mounted upon the shoe sole mould, and thepolyurethane-forming material is allowed to foam, whereby it will becomeadherent to the bottom of the upper. The shoe sole mould and last areremoved from the product and the product is generally allowed to cure.Adhesion of the upper to the foamed sole is due solely to the expansionof the foam.

Shaped inserts may be incorporated into the sole during the mouldingprocess, and, if desired, a releasable lm may be used to insureseparation from the mould.

It is thus an object of the present invention to provide a method ofmaking footwear in which a liquid, polyurethane foam-forming materialintroducted into a shoe soleforming mould having a recess of the shapeof a shoe sole in which adhesion ofthe shoe sole to the upper iseffected only by the expanding pressure of the foam.

It is a further object to provide a foamed shoe sole process in whichthe density of the foam can be altered by varying the initialtemperature of the shoe sole-forming mould.

It is an additional object to provide a process for forming a foamedcoherent shoe sole with shaped inserts of rubber, synthetic resin ormetal in the surface of the shoe sole.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinalcross-sectional view of an assembly of a shoe upper and a sole mountedon a last;

FIG. 2 is a cross-sectional view shown the pouring of a liquidpolyurethane-forming mixture into a shoe sole forming mould;

FIG. 3 is a cross-sectional view showing the assembly of the shoesole-forming mould and last;

FIG. 4 is a plane view of an assembly of the soleforming mould and last;

FIG. 5 is a longitudinal cross-sectional view showing a mould releasingfilm on the moulding surface of a shoe sole-forming mould; and 4 FIG. 6is a How-sheet diagrammatically illustrating an embodiment of lthemethod of this invention.

FIG. 7 is a longitudinal cross-sectional view of an assembly showing theincorporation of a urethane-rubber plate insert into a sole formed on asole-forming mould.

FIG. 8 is a longitudinal cross-sectional view of an assembly showing theincorporation of a spike-type insert into a sole forming on asole-forming mould.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The object of the presentinvention is to provide footwear and a method of making it in which inliquid, polyurethane foam-forming material is poured or introduced intoa shoe sole-forming mould having a recess of the shape of a shoe sole.Adhesion of thel sole thus formed f' Patented June 4, 19741 ofpolyurethane foam to the upper, carried byia last'fis effecfedhonly bytheasxpandins PressureV 0f the foam-VV The density of the foam can bealtered by varying the initial temperature of the shoe sole-formingmould.

In a modification of the ymethod of theA present invention, to the wholeor a portion of the moulding surface of the shoe sole-forming mouldthere are lfitted shaped bodies of rubber, synthetic resin or metal. Tothe space between the mould and a last bearing a shoe upper there isintroduced a defined quantity of a liquid, polyurethane-formingmaterial. The polyurethane-forming material is then allowed to foam tofill up the space and form a coherent body with the shaped bodies toform a shoe sole adherent to the bottom of the shoe upper.

In another modification of the method of the present invention, in themanufacture of footwear with a polyurethane sponge sole by pouring aliquid, polyurethaneforming composition into a shoe sole-forming mouldhaving a recess of the shape of a shoe sole, a mold releasing film ofsynthetic resinous material capable of being easily separated from thepolyurethane sponge sole thus formed is applied to the moulding surfaceof the shoe sole-forming mould prior to pouring of the liquid,polyurethane-forming composition.

In still another modification, the shoe sole-forming mould is made outof a synthetic resin which Will be easily separable from thepolyurethane sponge to be formed therein.

In still another modification, the shoe sole-forming the fiow-sheet ofFIG. 6, there may be used as shoe upper material, either alone or incombination, leather, textile fabrics, vinyls, artificial leathers,papers or like sheet materials. The shoe upper 1 sewn up as shown inFIG. 1, is combined with a bottom member by sewing into a bag and thebag is put on a last 22. Alternatively, the shoe upper may lbe mountedon a last with an inner sole member and, optionally, a core member as inusual practice. 'Ihe shoe sole mould is composed of a bottom 10 and sidewalls 2, 3 and may be of split type or non-split type. The shoe solemould is maintained at a definite temperature within a range from a lowtemperature to the elevated, curing temperature of the foam to be formedcorresponding to the desired physical properties of the foam. 'Ihen intothe shoe sole mould maintained at the definite temperature there isintroduced a liquid, polyurethane-forming mixture through a nozzle 21.Although the liquid, polyurethane-forming mixture cast into the mouldforms a water level within a short period of time owing to its lowviscosity even if poured through a fixed nozzle, the nozzle may be movedduring pouring or the shoe sole mould may be moved. There may also beemployed a plurality of nozzles for pouring of the liquid mixture. Thefeed rate of the liquid mixture may be the same or different at everynozzle. One may choose any of these systems according to the type ofsort of the footwear to be manufactured and/or to the workingconditions. In cases of employing a plurality of nozzles, one or more ofthe nozzles may be fed with a different liquid, polyurethane-formingmixture to form a foam with locally different densities. This may alsobe attained by locally var'ying the temperature of the mould.

In an embodimentof the present invention which comprises (1) puttingorvforming on the whole or portion of the-.moulding surface of the shoesole mould shaped bodies of rubber, syntheticresin or metal, (2) pouringor casting a liquid, polyurethane-forming mixture into the space betweenthe shoersole mould and a last bearing a shoe upper, (3) allowing theliquid mixture to foam to fill up `the space and becomeadherent to thebottom of the shoe Yupper and to kthe shaped bodies to form a shoe sole,the problem of wearing down of the shoe sole is at leastpartly'solved byusing abrasion resistant shaped bodies in a manner such that they willlocate in positions in the shoe sole at which the shoe soleundergoesviolent abrasive actions, and by use of non-skid metals as theshaped bodies shoe soles with non-skid metal are obtainable. Thus, shoesoles of various characteristics may be easily prepared by using variousshaped bodies asV inserts. In the case of using shaped bodies of pooradhesion to the polyurethane form, the shaped bodies should bepretreated with a material, c g., a urethane-based cement,neoprene-isocyanate cement, neoprene-phenolic resin cement or epoxycement to improve adhesion. After casting a liquid, polyurethane-formingmixture into the recess of the shoe sole mould in an appropriateprocedure, as set forth above, a last on which a shoe upper has beenmounted is put on and lightly pressed to the shoe sole moulds for aperiod of time. During this period, the liquid mixture foams and fillsup the space between the last and shoe sole mould and the curing of theliquid mixture proceeds. Although, in this case, the liquid,polyurethane-forming mixture is poured into the mould prior to fittingof the last to the mould, the liquid mixture may be introduced into thespace between the mould and last through an inlet formed in the bottomor side wall of the mould, after fitting of the last to the mould byinserting the nozzle in the tapered inlet hole or through-hole in themould. Also, in the latter case, there may be employed a plurality offeed nozzles.

Prior to the introduction of the liquid, polyurethaneforming mixture,the temperature of the shoe sole mould is adjusted to and maintained ata temperature between 10 C. and 90 C., most preferably 20 C. and 80 C.Then a defined quantity of the liquid mixture is introduced into themould and the last on which a shoe upper has been mounted is put on themould. The whole is then maintained at the temperature for about l0minutes to perform the primary curing of the liquid mixture to such anextent that the liquid mixture becomes a solid capable of being takenout of the mould. Then the shoe sole thus formed is taken out of themould together with the last which bears the shoe upper and is allowedto stand at room temperature or in a heating chamber until it isproperly cured. Thereafter, the last is removed from the finishedproduct. Though it is preferable to conduct the curing in two stages forthe sake of the turnover rate of the mould, it may be conducted in onestage. In the latter case, there may be employed a shoe sole mouldprovided with electric heating means. On occasions, the curing may beconducted by maintaining the mould at a temperature below 20 C., orabove 80 C.

In this method of manufacture, the density of the polyurethane foam isdefined by the temperature of the shoe sole mould before introduction ofthe liquid, polyurethane-forming mixture, so that the initialtemperature of the mould should be chosen and maintained during theprimary curing at the temperature depending on the desired properties.When the liquid, polyurethane-forming mixture (2) is introducted intothe shoe sole mould while maintaining the mould at room temperature orlower temperature, there is obtained a foamed shoe sole with highrigidity, is suitable for use as a shoe sole and is a foam having astrong skin layer. The lower the temperature of the shoe sole mould, thehigher is the rigidity of the resulting foam, since expansion of thefoam is restrained, so that there is obtained a foam of low water andsoil absorbing properties. The interior portion of such foams is of alower density. Accordingly, it is preferred to obtain foams of suchquality. The data below illustrates the relationship between the initialtemperature of the forming mould and the average density of the finalshoe sole:

Initial mould tem- Average density of vOrl theV contrary, when the shoe'sole -mould is maintained atafhightemperature during "inti'oductio'ri fthe liquid, polyurethane-forming'mixture, there is obtained a foam ofa'uniform density throughout the interior and exterior thereof.Therefore, it is possible'to'make Ashoe soles of light weight. However,the" shoe sole thus formed has `therdefects ofjabsorbing water and soilto some extent. Therefore, it is mostA preferred-to heat the liquid,polyurethane-forming mixture v20 to al temperature as high aspossibleAjust before' introductioninto the mould and to maintain the shoesole'mould at a low temperature soas to obtain a foam having a highdensity surface portion and a low-density inner portion. However, thecuring time required is prolonged to some extent in this manner. Thus,as mentioned above, the rigidity of the foam depends upon thetemperature of the shoe sole mould and, therefore, a foam of desiredproperties can be obtained by an appropriate choiceof the mouldtemperature just before introduction of the liquid, polyurethane-formingmixture thereinto.

' As illustrated Ain the Figuresofthe drawing, the shoe sole mouldconsists of a bottom member and a pair of side wall members 2, 3yfastened together by means of,

eg., bolts andnuts 4, 5 so as to clamp the bottom member.

The last is lightly pressed against the shoe sole mould by means of alever or screw-type pressure member 16 mounted to frames 18, fixed tothe bottom member 10 by pins 19. In some instances, the pressure membermay be replaced by a weight. To a portion of the peripheral surface ofthe last opposite the interior peripheral edge 9 ofthe side wall of theshoe sole mould there may be applied a rubber tape or tape of arubber-like elastomeric material as to prevent damage of the shoe upperand to prevent leakage of the liquid, polyurethane-forming mixture 20.In order to obtain the same effect, a rib formed of rubber orrubber-like elastomeric material of various rigidities may be vfixed bymeans of pins and bolts to the interior peripheral edge of the side Wall2, 3 in place of the protrusion 9 on the interior peripheral edge.

A mould releasing film may be applied to the inside surface of the shoesole mould. In this modification, a seamless film or sheet ofpolyethylene, polypropylene, polystyrene or like synthetic resinousmaterial that is easily kseparable Vfrom the polyurethane foam isapplied to the recess of the shoe sole mould by a vacuum forming processorrother film forming process. To the recess thus covered with a mouldreleasing film or sheet there is cast a liquid, polyurethane-formingmixture 20 which will foam into a polyurethane foam sole adherent to ashoe upper in the recess. For instance, asv illustrated in FIG. '5, ashoe sole mould consisting of a bottom member 10 and a pair of side wallmembers 2, 3 is built up and clamped by bolts 4, 5. The bottom and sideWall members have suction holes 6, 7, 8 and the jointsof the members aresealed with O-rings or like rubber packings. A film or sheet 17 ofsynthetic resinous material is put on the side 'wall members 2, 3 as tocover the cavity of the shoe sole mould and is air-tightly clamped bymeans of frame 14 and clamping bolts 1S. Then the synthetic resin filmor sheet is uniformly heated by means of an infrared heater locatedabove the -film or sheet and the cavity of the shoe sole mould isevacuated through the suction holes 6, 7, 8 to form a mould releasingfilm in conformity with the recess or cavity of the shoe sole mould. Onthe mould releasing film there is cast the liquid, polyurethane-formingmixture. However, in order to increase the production rate, it ispreferred to form the mould releasing film separately using afilm-forming mould having the same contour with the shoe sole mould andto put the so previously formed film into the shoe sole mould justbefore introduction of the liquid, polyurethane-forming mixture. Thisprocess where a mould releasing Kfilm is employed is economical since,in this process, leakage of the liquid polyurethaneforming mixturethrough the joints of the bottom and side wall members of the shoe solemould is prevented, so

that a constant and appropriate amount of the liquid mixtre'is retainedinthe mould, a product of a uniform density is obtained, occurrence offailures is avoided and the finishing of the products to eliminate ushestherefrom is unnecessary. Moreover, though it is necessary, when themould releasing film is not employed, to retain the cast liquid,polyurethane-forming mixture within the mould for at least yabout 10minutes in order to avoid failure upon withdrawal from the mould even ifa mould releasing agent or mould lubricant is applied to the mouldsurface, the last can -be Withdrawn from the mould after retention ofonly about 5 minutes without any failure of the shoe sole thus mouldedusing the mould releasing film.

Alternately, products of good quality may be obtained without using anymould releasing agent or mould lubricant by employing a shoe sole mouldformed of polyethylene, polypropylene, polystyrene or like syntheticresinous material, which is separable from polyurethane foams with nodiiculty, casting a liquid, polyurethaneforming mixture, in the mannermentioned above, into the mould, and allowing the liquid mixture to foamand directly adhere to the shoe upper.

FIGS. 7 and 8 illustrate the incorporation of inserts into the foamedshoe sole of the present invention. In both figures, 7 represents asuction hole which holds the inserts tightly against the bottom 10 ofthe mould while the polyurethane-forming mixture 2 is being Ifoamed.

Specifically, in FIG. 7, after a colored urethane-rubber plate 23 wasput into the mould, the liquid urethane was poured into the mould. Theurethane-rubber plate 23 has a solidity of about 5060 (I IS), and due tothe foaming pressure the plate is pressed against the lower part of themould. In this ease, as the air is forced out from beneath the plate viasuction hole 7, the urethane-rubber plate easily conforms to the surface0f the mould. Of course, the suction holes 7 can be replaced by mereventing holes, since the foam pressure will suflce to press the plateagainst the mould.

When using an ordinary rubber plate, usually some suitable adhesiveagent is applied or a cotton cloth is attached to the face whichcontacts the foaming sole per se.

FIG. 8 is similar to FIG. 7, but shows the use of a spike-type insert 24which may be metal, rubber or the like.

EXAMPLE 1 1 mole of a poly(epsilon-caprolactone) diol of a molecularweight of 1,000 and 2 moles of tolylene diisocyanate were reacted at C.,for 2 hours to form an isocyanate-terminated pre-polymer of a freeisocyanate content of 6%. 100 parts of the pre-polymer maintained at 70C., 17 parts of 4,4-methylene-bis (2-chloroaniline) at 110 C., 0.2 partof tin octoate at room temperature, 2 parts of a silicone at roomtemperature and 0.14 part of Water at room temperature were quicklymixed together and the resutlng mixture was cast or poured into a shoesole mould maintained at 80 C. A last `which bore a shoe upper was thenfitted to the shoe sole mould and the whole was allowed to stand. Afterabout 10 minutes, the mixture could be withdrawn from the mould adheredto the last and upper. After sufficiently curing the sole, the last wastaken out. The foam thus formed exhibited a specific gravity of 0.40, amodulus of 15 kg./sq. cm., a tensile strength at break of 30 kg./sq. cm.and an elongation at break of 360%.

EXAMPLE 2 1 mole of a poly(oxytetramethylene)glycol was reacted with 2moles of tolylene diisocyanate at 80 C., for 2 hours to form anisocyanate-terminted pre-polymer of a free NCO content of 6%. 100 partsof the pre-polymer thus formed with quickly mixed together with 17 partsof 4,4-methylene-bis(2-chloroaniline), 2.2 parts of dibutyltindilaurate, 1.5 parts of a silicone and 0.14 parts of water and themixture was poured into a shoe sole mould maintained at 80 C. 'Ihen alast which bore a 7 shoe upper was fitted to the mould and the whole wasallowed to stand still. After 30 minutes, both the last and shoe solemould could be with drawn -or removed from the product. The foam thusobtained exhibited similar properties as in Example 1.

EXAMPLE 3 1 mole of a po1y(oxytetramethy1ene)glycol of a molecularweight of 1,000 was reacted withy 2.5 molesl of diphenylmethanediisocyanate at 80 C., for 2 hours to form an isocyanate-terminatedpre-polymer of a free NCO content of 7%. 100 parts of the pre-polymerthus formed was quickly mixed together with 4.5 parts of ethyleneglycol, l part of a silicone, 0.25 part of tetramethylbutane diamine and0.1 part of water and the mixture was cast or poured into a shoe solemould maintained at 20 C. Then a last which bore a shoe upper was fittedto the mould and the assembly was allowed to stand for about 10 minutes.The mould was then removed and, after completion of curing, the last wasremoved. The foam thus obtained exhibited a specic gravity of 0.6, a100% modulus of kg./ sq. cm., a tensile at break of 87 kg./sq. cm. andan elongation at break of 390% EXAMPLE 4 Using a polyester in place ofthe polyether as in Example 3 in preparation of the pre-polymer, asimilar result was obtained.

EXAMPLE 5 100 parts of a poly(epsilon-caprolactone)glycol maintained at50 C., was quickly mixed together with 71 parts of diphenylmethanediisocyanate (40 C. 9 parts of ethylene glycol (room temperature), 1.5parts of a silicone (at room temperature), 0.17 part of water (at roomternperature) and 0.01 parts of dibutyltin dilaurate (at roomtemperature) and the mixture was cast or poured into a shoe sole mouldat 20 C. Then a last which bore a shoe upper was fitted to the mould.The whole was then allowed to stand for about 10 minutes and the mouldwas removed. After completion of curing, the last also was removed. Thefoam thus obtained exhibited properties similar to the product ofExample 3.

What is claimed is:

1. In a method for making footwear having a sole formed of apolyurethane foam comprising:

(l) mounting a last which bears a` shoe upper thereon on a shoe solemould, the last bearing said upper being forcibly held against the shoesole mold to define an initial space therein between said mould and saidupper;

(2) casting a quantity of a low viscosity, liquid, polyurethanefoam-forming mixture into said initial space wherein said foam-formingmixture is substantially at its foaming temperature;

(s) foaming said foam-forming mixture to form a 55 264-45, 244, 33s

foamed sole; and (4) removing the mold and the last from the foamed soleand curing the foamed sole; the improvement comprising regulating .fthespecific gravity or bulk v density of said sole by maintaining saidinitial space `constant during molding,-maintaining .said moldat aninitial temperature ofw from .l0 to. 90l C., a higher 1 temperatureproviding a foam of relativelyA lower Y -density and'likewise; a lowertemperature proyidi'ng foam of relatively higher density, andallowin'glthe foam-formingdmxtnre in the moldrto foam 'and fill y v upsaid constant initial-space whereby adhesionof -I resulting foamed soleto the shoe upper is due solely to the pressure exerted bythe expandingfoamagainst said shoe upper carried by the last and held against saidmold, thereby forming ay single piece unitary f sole. v Y

2. The method of claim 1 wherein the mould is in aintained at an initialtemperature of from 20 to 80 C.N y

3. The method as defined in claim`1` further comprising placing on thebottom moulding surface of the shoe sole mould at least one shaped bodyto which said sole is adhered concurrently with adherence of said soleto said upper.

4. The method as defined in claim 1 further comprising fitting therecess of the shoe sole mould with a releasing lm which is easilyseparable from the polyurethane foam.

S. The method of claim 4 wherein said releasing film is vacuum fitted tosaid shoevsole mould.

6. The method of claim 5 whereinsaid releasing film comprises asynthetic resin selected from the group consisting of polyethylene,polypropylene and polystyrene. v

7. The method as defined in claim 1 further comprising forming said shoesole mould from a synthetic resin which is easily separable from thepolyurethane foam.l

8. The method of claim 7 wherein said synthetic resin is selected fromthe group consisting of polyethylene, polypropylene and polystyrene.

9. The method of claim 1 further comprising maintaining the temperatureof the mould at a temperature no greater than room temperature so thatthe foamed sole has a dense skin layer and a less dense core.

References Cited STATES PATENTS DONALD E. CZAJA, Primary Examiner R. W.GRIFFIN, Assistant Examiner y U.S. Cl. X.R.l

